Phil and his colleagues investigated the use of the audio commenting tool in Adobe Acrobat Pro to provide audio feedback on student assignments in an online course.

The experimental design and analysis was rigorous with aspects such as alternating between text-based and audio-based feedback types between assignments throughout the term, a question on the final course survey asking for student preference for audio versus text-based feedback, and 27 post-course interviews with students, etc.

The project started off on the right foot when 40% of students spontaneously emailed the instructor about the first occurrence of audio commenting with all of those emails expressing satisfaction with the technique.

On the end-of course survey, the results remained impressive. 26 students preferred audio to text, 4 students indicated no preference and one answer N/A (due to a defective sound card).

The transcript analysis of the 27 post-course interviews with students revealed four themes:

Ability to understand nuances in feedback (70% of students). Humor, tone, encouragements and emphasis were much easier to interpret using the audio feedback.

Feelings of increase involvement (56% of students). The connection between instructor and student seemed to be increased and consequently students were engaged in their online course.

Content retention (44% of students). Students reported that they retained the content of the audio feedback better that text-based feedback.

Instructor caring (30% of students). Students reported that audio feedback was more personal than text and they perceived the instructor as caring more when he left an audio message.

Phil and his colleagues actually did more analysis than I am describing here, but you get the idea. If you would like to see his PowerPoint presentation from Banff you will find it hosted at SlideShare and if you would like to see a recent article on this subject then this is a good one: